Piston assemblies normally used are made of steel and hardened to increase their wear life. In the known piston assemblies, a slipper is pivotally connected to a piston so that one part can pivot relative to the other. In these piston assemblies, a spherical cavity is in one of the components and a spherical ball is disposed on the other component. Upon assembly, the spherical ball is placed in the spherical cavity and mechanically retained therein. During all pivotal movement of the spherical ball in the spherical socket, the outer surface of the spherical ball is in sliding contact with the surface of the spherical cavity. Since there is sliding contact and heavy loading between the spherical ball and the spherical cavity, a lubricant is continually needed between the surfaces in order to eliminate scoring and/or seizing of the surfaces. The sliding friction between the metal surfaces creates undesirable heat and wear between the components. Furthermore, it is necessary to maintain close tolerances of size, sphericty, and surface finish on the spherical ball and the cavity that it fits into.
The present invention is directed to overcoming one or more of the problems as set forth above.